Preheat the oven to 325 degrees on the convection setting, if you have it. Line a baking sheet with parchment paper. Arrange two small 6-inch ceramic baking dishes on top and set aside. Coat the bottom and sides of each baking dish with ½ teaspoon of olive oil (or butter).
In a small bowl, stir together the cream, Gruyère, and finely grated butter.
Gently crack two eggs into each baking dish, taking care not to break the yolks. Using a small rubber spatula, poke through the thicker portion of the egg white a few times to break it up and allow for more even cooking.
Dollop the cream mixture evenly over the egg whites, avoiding the yolks.
Place in the oven to bake until the egg whites are just set and the yolks are still runny, 10 to 12 minutes. Side Note: If you are not using your convection setting, this dish will take longer, about 18 to 20 minutes.
Remove from the oven, sprinkle with thyme leaves, Portuguese flor de sal (or Maldon salt), and freshly cracked black pepper to taste.
Serve immediately, with buttered toast for dipping, if desired.